The measurement of temperature during the refining or processing of metals is a common requirement throughout the industry. A measurement of the liquidus arrest temperature (i.e., the temperature at which the molten metal begins to solidify) is important for determining the analytic content of the metal alloy in the bath prior to pouring or casting of the metal. In particular such temperature measurements can be correlated to the level of carbon in cast irons or steels. In many applications, the measurement of both the molten metal temperature in the bath and the phase change temperature is desirable.
Typical measuring probes which measure both the bath and the phase change temperature consist of two separate thermocouple elements. One thermocouple element is exposed to the molten bath while the second thermocouple element, contained within a defined chamber, is exposed to a sample of both as it initiates a phase change from the molten state. Such probes require not only two thermocouple elements but also include additional hardware and electrical connections. Additionally, since two separate temperatures are being measured substantially simultaneously, the components which record and register the separate temperatures require separate read out portions. By doubling the structural and the operational requirements, additional cost is added to the production and operation of a two temperature measuring device.